public class MyUtil {
    public static  String percentage2fivegrade (int grade){
        if(grade <0 ||grade >100)
            return "错误";
        else if (grade < 60)
            return "不及格";
        else if(grade < 70)
            return"及格";
        else if(grade < 80)
            return "中等";
        else if(grade < 90)
            return"良好";
        else if(grade <=100)
            return "优秀";
        else return "错误";
    }
}
